In recent years, gallium nitride compound semiconductor light-emitting devices have drawn attention as short wavelength light-emitting devices. The gallium nitride compound semiconductor light-emitting device is obtained by forming a gallium nitride compound semiconductor on various kinds of substrates, such as a sapphire single crystal substrate, an oxide substrate, and a group III-V compound substrate, by a metal organic chemical vapor deposition (MOCVD) method or a molecular beam epitaxy (MBE) method.
In the gallium nitride compound semiconductor light-emitting device, a small amount of current is diffused in the horizontal direction. Therefore, a current is applied to only a semiconductor immediately below an electrode, and light emitted from a light-emitting layer is shielded by the electrode, which makes it difficult to emit light from the light-emitting device to the outside. In order to solve this problem, in the gallium nitride compound semiconductor light-emitting device, a transparent electrode is generally used as a positive electrode, and light is emitted to the outside through the positive electrode.
In the related art, the transparent electrode has been formed of a known transparent conductive material, such as Ni/Au or ITO.
In recent years, the transparent electrode has generally been formed of an oxide material including, for example, In2O3 or ZnO having high translucency as a main ingredient. In ITO (indium tin oxide) that has been commonly used as a material forming the transparent electrode, In2O3 is doped with 5 to 20 percent by mass of SnO2 to form a transparent conductive film having a specific resistance of about 2×10−4 Ωcm.
Since the ITO film has a band gap of 3 eV or more, it has high transmittance with respect to light in the visible wavelength range (>90%). However, since the ITO film mainly absorbs light in a wavelength range of about 400 nm or less, the transmittance of the ITO film is rapidly reduced in the wavelength range of 400 nm or less. Therefore, when the ITO film is used as an electrode of a light-emitting device that emits light in an ultraviolet wavelength range, emission power is lowered.
In order to solve this problem, a light-emitting device has been proposed which prevents ultraviolet rays from being absorbed by a transparent electrode and converts the ultraviolet rays into visible light before the ultraviolet rays reach the transparent electrode (for example, see Patent Document 1).
In addition, in order to reduce the amount of light absorbed by the transparent electrode, a face-up light-emitting device including a through hole for light emission and an adhesive metal layer having high reflectance has been proposed (for example, see Patent Document 2).    [Patent Document 1] JP-A-5-299175    [Patent Document 2] JP-A-2005-123501